MODBUS_SET_SLAVE(3) Libmodbus Manual MODBUS_SET_SLAVE(3)
NAME
modbus_set_slave - set slave number in the context
SYNOPSIS
int modbus_set_slave(modbus_t *ctx, int slave);
DESCRIPTION
The modbus_set_slave() function shall set the slave number in the libmodbus context.
The behavior depends of network and the role of the device:
RTU
Define the slave ID of the remote device to talk in master mode or set the internal slave ID in slave mode. According to the protocol,
a Modbus device must only accept message holing its slave number or the special broadcast number.
TCP
The slave number is only required in TCP if the message must reach a device on a serial network. The special value MODBUS_TCP_SLAVE
(0xFF) can be used in TCP mode to restore the default value.
The broadcast address is MODBUS_BROADCAST_ADDRESS. This special value must be use when you want all Modbus devices of the network receive
the request.
RETURN VALUE
The modbus_set_slave() function shall return 0 if successful. Otherwise it shall return -1 and set errno to one of the values defined
below.
ERRORS
EINVAL
The slave number is invalid.
AUTHORS
The libmodbus documentation was written by Stephane Raimbault <stephane.raimbault@gmail.com[1]>
NOTES
1. stephane.raimbault@gmail.com
mailto:stephane.raimbault@gmail.com
libmodbus 3.0.3 05/26/2012 MODBUS_SET_SLAVE(3)